Launching X11 manually ./X11 is a good point. Did that and XQuartz appears in the dock. Firing then xclock on the Target doesn’t do a connection. Silence. The xclock just hangs there.
I don’t see any listening socket: kuku@Christophs-MBP ~ % ps ax | grep -i x11 88342 ?? Ss 0:00.81 /opt/local/libexec/privileged_startx -d /opt/local/etc/X11/xinit/privileged_startx.d 6254 s003 S+ 0:01.61 ./X11.bin 6258 s003 S+ 0:00.02 /bin/sh /opt/X11/bin/startx -- /opt/X11/bin/Xquartz 6305 s003 S+ 0:00.00 /opt/X11/bin/xinit /opt/X11/lib/X11/xinit/xinitrc -- /opt/X11/bin/Xquartz :0 -nolisten tcp -iglx -auth /var/root/.serverauth.6258 6306 s003 S< 0:00.00 /opt/X11/bin/Xquartz :0 -nolisten tcp -iglx -auth /var/root/.serverauth.6258 6405 s003 S 0:00.03 /opt/X11/bin/quartz-wm 10624 s005 R+ 0:00.00 grep -i x11 kuku@Christophs-MBP ~ % lsof -U | grep 6254 kuku@Christophs-MBP ~ % lsof -U | grep 6258 kuku@Christophs-MBP ~ % lsof -U | grep 6305 kuku@Christophs-MBP ~ % lsof -U | grep 6306 kuku@Christophs-MBP ~ % lsof -U | grep 6405 kuku@Christophs-MBP ~ % lsof -U | grep 88432 kuku@Christophs-MBP ~ %